Using a moving diffraction grating to simulate the function of an acousto‐optic modulator

We present an instructional undergraduate laboratory that introduces the student to an acousto‐optic modulator (AOM) in the context of an optical heterodyning experiment. A moving diffraction grating is used to illustrate the internal functioning of an acousto‐optic modulator and to make optical heterodyning experiments accessible to any undergraduate laboratory. The concepts and techniques presented can be used from the introductory through advanced level, in that, students gain direct laboratory experience with diffraction, the Doppler shift of light, construction of a Mach–Zehnder interferometer, optical path length measurements using a heterodyne technique, and sophisticated data analysis techniques.